DE68912493T2 - Vacuum toilet system. - Google Patents

Abstract

A vacuum toilet system for a vehicle (e.g. an aircraft) uses grey water from a wash basin (40) to rinse a toilet bowl (2) during flushing of the latter. The grey water is collected in a reservoir (62) and passed into the bowl (2) by a pump (118) operated by the vacuum in the sewer pipe (8) to which the bowl (2) is connected. <IMAGE>

Description

This invention relates to a vacuum toilet system for use in a transport vehicle.

Vacuum toilet systems have been known for many years. A modern vacuum toilet system includes a waste receiving bowl, a suction line that can be maintained at a pressure significantly less than that inside the waste receiving bowl, and a discharge valve for controlling the passage of material from the waste receiving bowl into the suction line. A flushing fluid outlet port is provided near the rim of the waste receiving bowl and is connected to a pressure flushing fluid supply via a flushing fluid valve. During a flush cycle, in which the discharge valve is open, the flushing fluid valve is opened and flushing fluid is introduced into the waste receiving bowl.

Non-recirculating vacuum toilet systems that use ordinary water as the flushing liquid are advantageous for use in aircraft. In such a system, the flushing liquid is taken from the aircraft's drinking water system in a conventional manner. The drinking water system includes a tank, pipes connecting the tank to consuming devices, such as the vacuum toilets and hand basins, and a pump for generating water pressure in the pipes.

An aircraft lavatory system includes a collection container to receive waste material from the waste-receiving bowl. To avoid transporting material that could be discharged from the aircraft during flight, grey water, i.e. water that, although not potable, can be discharged into the environment without further treatment, e.g. water from hand basins and kitchen sinks, is not discharged into the vacuum toilet system so that it reaches the collection container, but is discharged from the aircraft via a discharge mast.

US-A-4,713,847 shows a vacuum toilet system in which a pump is used to supply flush water to a toilet bowl under control of a valve which is opened in response to the actuation of a flush button.

FR-A-2 286 922 discloses a water supply and waste disposal system for a transport vehicle in which a vacuum in a suction line is used to withdraw waste material from the waste receiving bowl of the system. The system includes water use units and a reservoir for collecting the grey water from these units. A flush water pump, operated by closing the bowl lid, is used to supply collected grey water to the waste receiving bowl for flushing it.

Throughout the specification and claims, references are made to location terms such as "above" and "below," "upper" and "lower," "top" and "bottom," it being understood that these terms refer to the relative locations when the vehicle is moving horizontally (e.g., the aircraft is in balanced, i.e., level, flight). The use of these and similar terms to denote relative positions is used for clarity in describing the system and should not be interpreted to limit the use of the invention to the horizontal attitude of the vehicle.

The invention is defined in the following claims 1, 5 and 9, the preamble of these claims being delimited against FR-A-2 286 922.

In accordance with the invention, the lower pressure generated in the bowl when the lid is closed and the discharge valve is open, is used to direct grey water into the bowl for flushing.

The invention will now be described in more detail by means of an embodiment with reference to the accompanying drawing. In this drawing:

Fig. 1 is a schematic, partially sectioned view of a vacuum toilet system according to the invention and

Fig. 2 shows a section IV-IV from Fig. 1.

The vacuum toilet system shown in Fig. 1 is intended for installation in a pressurized aircraft and includes a toilet bowl 2 having an interior for receiving waste material and an outlet opening 4. The outlet opening is connected to one side of an electrically operated discharge valve 6 and the opposite side of the discharge valve is connected to a receiving container (not shown) via a suction line 8. The discharge valve 6 controls the flow of material from the toilet bowl to the receiving container. A pressure differential of approximately 250 millibars is required to operate the system shown in Fig. 1. A sufficient pressure differential to operate the system exists between the cabin of the aircraft and the ambient atmosphere when the aircraft is at an altitude of more than 5000 m. If the pressure difference between the cabin of the aircraft and the ambient atmosphere is insufficient, a fan (not shown) is used to create a sufficient pressure difference. For further information regarding the manner in which the material is transported to and removed from the container, reference is made to US-A-4,713,847.

The vacuum toilet system further includes a hand basin 40 with a cold water valve 42 and an outlet line 44. The cold water valve 42 is connected via a line to a pressurized water source, not shown. The cold water valve 42 is electromagnetically operated and closes automatically. When a user presses a push button (not shown), a switch is closed to supply electrical current to the electromagnet which opens the valve 42. When the electrical current is removed, eg when pressure is removed from the button which keeps the switch closed, the valve 42 closes again.

The outlet line 44 of the hand wash basin 40 is connected to a grey water reservoir 338. The grey water reservoir includes a lower housing 342 and an upper housing 340.

A flush control unit 180 receives input signals from a flush trigger switch 182, which is controlled by a flush control button (not shown), and provides output signals to control the state of the dispensing valve 6 and the water valve 42. The flush control unit 180 could also receive other input signals and provide other output signals, but these do not relate to the present invention and are therefore not discussed.

When the flush control button is pressed, the switch 182 is closed and the unit 180 responds by initiating a flush cycle. During the flush cycle, the unit 180 opens and closes the discharge valve 6 to remove waste material from the bowl 2 and causes flush water to be supplied to the bowl 2. The unit 180 ensures that the vacuum in the collection container is sufficiently high, but the manner in which this is achieved does not extend to the invention and will not be described further. In this regard, reference is made to US-A-4,713,867. The present invention relates to the means by which the flush liquid is supplied.

The vacuum toilet system shown allows the use of grey water to flush the water-absorbing bowl 2 and thus reduces the amount of water that must be transported from an aircraft equipped with a vacuum toilet system without The system does not require all of the grey water to flush the toilet.

The waste receiving bowl 2 is mounted in an outer casing 300 spaced from the bowl. An air supply member 302 of molded synthetic polymer material is secured to the edge of the bowl 2 and bridges the space between the bowl 2 and the cover 300. The member 302 is generally annular and has a flange 304 extending downwardly into the bowl spaced from the inner surface thereof. Accordingly, an annular channel 306 is formed between the flange 304 and the inner surface of the bowl 2.

Disposed within the bowl 2 is a distribution line 320 which extends approximately 2/3 of the way around the bowl. The line opens into the annular channel 306 via three openings 324, one opening 324 at each end of the line 320 and one between the ends thereof. A baffle plate (not shown) is disposed at the front of each opening 324. In a variation of the system shown in Figures 1 and 2, the rinse water distribution line 320 could extend 3/4 of the way around the bowl 2 and have four openings spaced approximately equally around the bowl 2.

The flush water distribution line 320 is connected via a flush water supply line 328 to the reservoir 338 which collects grey water from the hand wash basin 40. The reservoir 338 is preferably located close to the bowl 2 to minimize the length of the line 328. However, it could alternatively be located directly under the hand wash basin 40 like an enlarged water collection container. The upper and lower chambers 340, 342 of the reservoir 338 are separated from each other by a wall 344 which is formed with a hole 346 for liquid flow. The flush water supply line 328 extends almost to the bottom of the lower chamber 342 and is provided with a small ventilation hole 350 directly under the top the upper chamber. The outlet line 44 is designed to ensure easy outlet into the reservoir 338. The overflow 88 is arranged near the reservoir 338 to minimize the amount of water in the line 44 when the reservoir is filled to the level of the overflow. The outlet line 44 is open into the lower chamber 342 and when the lower chamber is full, additional water fed into the lower chamber passes through the hole 346 into the upper chamber. When full, the lower chamber 342 contains enough water for one flush of the bowl 2, e.g. around 200 ml. The cabin pressure of the aircraft is fed through the outlet line 44, through the flush water supply line 328, the vent hole 350 and the hole 346 to the lower chamber 342.

The air supply part 302 is provided with numerous holes 352 which extend into the channel 306. The holes 352 are spaced apart around the part 302. In a practical embodiment of the invention, eight such holes 352 may be provided. For clarity, the holes 352 shown in Fig. 1 extend radially, but in fact the holes are inclined at an angle of 50 to 100 relative to the radial direction and all holes extend into the channel 306 counterclockwise with respect to the part 302 in plan view. The air supply part 302 is provided with grooves on its upper surface. The grooves 358 extend semi-tangentially with respect to the part 302 and are all directed inwardly counterclockwise in plan view. Of course, the holes 352 and the grooves 358 could extend into the toilet bowl 2 in a clockwise direction instead of counterclockwise.

The bowl 2 is provided with a seat 360 and a lid 362. The seat and lid are hinged to the air supply part 302 with a hinge 364. When the seat 360 is lowered, it engages the air supply part 302 and closes the grooves 350 on the top. The seat 360 is provided with a gap 366 at the front of the toilet bowl. The lid 362 is designed such that when it is lowered, the cabin of the aircraft is not in direct open communication with the interior of the toilet bowl through the gap 366. The purpose of the gap 366 is to create a rapid air flow directed into the toilet bowl, thereby avoiding the formation of negative pressure in the bowl in the event of a malfunction causing the valve 6 to open when the toilet is in use.

The lid 362 actuates the flush trigger switch 182, which is only shown schematically in Fig. 1. The switch 182 is automatically closed when the lid is closed and remains open when the lid is open.

When the lid 362 is lowered, the flush control unit 180 generates a flush signal in response to the closure of the switch 182 and the dispensing valve 6 is opened. A vacuum is applied to the interior of the bowl 2 and this vacuum ensures that the lid is pressed into a tight, sealing engagement against the seat. Due to the partial vacuum that has been created in the interior of the bowl 2, air is directed into the interior of the bowl via the grooves 358 and the openings 352. The air flowing into the annular channel 306 via the holes 352 has a substantially lateral velocity component and therefore exerts a swirling motion over the interior of the bowl. The air flowing into the toilet bowl via the grooves 358 exerts a similar swirling motion.

When a partial vacuum has been created in the toilet bowl, the vacuum is transferred to the water supply line 328 via the openings 324 and the water distribution line 320. The water is drawn from the lower chamber 342 into the line 328 and discharged into the channel 306 via the openings 324. The water exiting the line 320 via the openings 324 strikes the baffles (not shown) which cause the water to spray upward and sideways. The water entering the channel 306 is incorporated into the vortex air stream from the holes 352 and performs a similar vortex movement, cleaning the inner surface of the bowl. The air stream transfers kinetic energy to the flushing water stream and thus improves the cleaning effect of the water. The vortex movement of the air and water in the bowl can generate a spray mist which can rise up into the space defined by the inner surface of the flange 304 and result in a precipitation of mist droplets on the underside of the cover 362 and the seat 360. This upward rising of the mist is prevented by the air stream supplied via the grooves 358.

When vacuum is applied to the water supply line 328, a small amount of air or water (corresponding to the level of fullness of the reservoir 338) is drawn from the upper chamber 340 into the line 328. When the liquid level in the lower chamber has fallen below the lower end of the line 44, air is drawn into the reservoir 338 through the vent 348. Because the air enters the lower chamber and passes up through the hole 346, the lower chamber is in a throttled connection with the upper chamber and the lower chamber is not refilled by gravity from the upper chamber during a flushing operation, but only when the flushing operation is completed.

When the dispensing valve 6 is closed, water from the upper chamber 340 enters the lower chamber 342, thereby refilling the lower chamber. Thus, the reservoir 338 acts as a metering device which dispenses a volume of water during each flush equal to the volume of the lower chamber plus the volume of water in the lines 44 and 328 above the level of the top of the lower chamber. To minimize variations in volume, the lines 44 and 328 should be relatively small, e.g., 1.25 cm in diameter.

The line 328 is inclined downwards towards the reservoir so that when a flush is completed, the fluid in the line remaining water flows back into the reservoir, minimizing greywater requirements.

In an aircraft, the degree of partial vacuum that is built up in the toilet bowl when the dispensing valve is opened can vary widely. Furthermore, the flush time in some aircraft vacuum toilet systems depends on the positioning of the toilet bowl (front or rear). Therefore, the reservoir 338 is designed such that with a low vacuum and a short flush time, the lower chamber of the reservoir is only barely emptied. With a higher vacuum and/or a longer flush time, the lower chamber is well emptied before the dispensing valve 6 is closed.

For the system shown in Figs. 1 and 2 to function properly, it is necessary that the flow resistances of the three paths for supplying air and water to the toilet bowl are balanced so that the functions of the different flows are achieved. Proper balancing of the flows is best achieved by experiment. It has been found, for example, that the greater part of the air flow should be supplied through the holes 352.

When the aircraft is first operated at the beginning of a workday, the flush control unit 180 automatically performs a start-up routine in which the hand basin valve 42 opens for a time sufficient to provide enough water for five flushes. The unit 180 counts the number of flushes during the day and the number of periods the hand basin valve is opened by manual operation and uses this information to determine whether the reservoir 338 is in danger of becoming empty. When the flush control unit determines that the reservoir is becoming empty, it causes the hand basin valve to open, thus supplying additional water to the reservoir. In this way, the need for a level gauge in the reservoir is eliminated. In addition, there is no need for fine spray nozzles because the water supplied through the outlet opening 324 is effectively distributed over the inner surface of the toilet bowl by the air flow entering the toilet bowl. Furthermore, no valves or pumps are arranged between the reservoir 338 and the openings 324. Accordingly, no filter is required and this in turn eliminates the need to allow cleaning of the filter. Of course, a screen plate can be provided in the outlet of the hand basin or in the outlet line 44 connected thereto to catch objects such as matches and buttons.

The swirling air stream introduced into the toilet bowl in the system of Figures 1 and 2 is very effective in cleaning the toilet bowl even without the aid of flush water. Therefore, in a modification of the system of Figures 1 and 2, the flush control unit 180 is designed without the ability to count the number of flushes, so that if the reservoir runs dry, the flush bowl is cleaned by the air stream alone. In fact, however, the tendency of the reservoir to run dry is relatively small because more grey water is normally generated by the use of the hand basin than is required for the toilet flushes.

The toilet system shown in Figs. 1 and 2 is not limited to aircraft application and a system similar to the one shown could be installed in a ship or, for example, in a train. In the case of a system intended for an application other than in an aircraft, factors relating to the type of installation could make changes necessary. For example, in the case of a system on a ship, where the volume of waste is not of interest because it is pumped overboard, the pipe 328 could be inclined towards the toilet bowl so that at the end of a flush the water in the pipe 328 runs into the toilet bowl and forms a puddle of water there. In a toilet system on a train the degree of vacuum and flushing time are not subject to great changes and therefore a simpler reservoir can be used. In such a Reservoir would have separate upper and lower chambers and the volume of greywater discharged with each flush would be determined only by the degree of partial vacuum and the flushing time.

If intended for use in an aircraft, the vacuum toilet system as shown in Figures 1 and 2 could be incorporated into a self-supporting module which is installed as a unit in the aircraft. The module contains a toilet bowl and associated discharge valve, a hand basin and a reservoir. The module is self-contained, except for the connections for the vacuum suction line, the potable water supply and, if necessary, the aircraft drainage system. In the above modification of the system shown, where no overflow line is provided, the implementation of the toilet module is facilitated because there is then no gravity line leaving the module.

The system described and illustrated is not limited to the specific number and arrangement of bores, openings and grooves, and it is not essential to the invention that the grooves be oriented to induce turbulence in the same direction of rotation as the swirling motion induced by the bores or openings. In fact, the grooves may be radially oriented so as not to induce turbulence at all. To promote the swirling motion of the air flowing through the openings 352, guide ribs may be provided on the radially outer surface of the flange 304, the ribs being inclined downwardly in a counterclockwise direction. Furthermore, although each system illustrated includes an overflow for excess grey water, such an overflow is not always essential. Thus, if the overflow 88 were omitted in the case of the system of Figures 1 and 2, the excess grey water would flow into the bowl 2 and then into the waste tank, and as long as the waste tank is large enough to accommodate the excess grey water, this would not present a problem.

Claims (10)

1. A water supply and waste disposal system for a transport vehicle, comprising a waste receiving bowl (2) with an outlet opening (4), a suction line (8), a normally closed discharge valve (6) connecting the outlet opening (4) of the bowl (2) to the suction line (8), a partial vacuum source for generating a lower pressure in the suction line (8) than in the bowl (2), a water usage unit (40), a water supply system (42) for supplying water to the water usage unit (40), a reservoir (338) with an inlet (44) for receiving flushing liquid from the water usage unit (40) and with an outlet (328) in communication with a flushing water outlet (324) in the bowl (2), the bowl (2) having a rim and a bowl lid (362) which is adapted for movement relative to the bowl (2) between an open and a closed position, which lid (362) is in at least partially sealed relationship with the rim when in the closed position, so that when the lid (362) is in the closed position and the dispensing valve (6) is open, a negative pressure is created in the bowl (2), characterized in that the inlet (44) of the reservoir is subjected to substantially the same pressure (P₁) as the rinse water outlet (324) when the lid (362) is in the open position and the dispensing valve (6) is closed, so that rinse liquid is drawn from the reservoir (338) via the rinse water outlet (324) into the bowl (2) when the lid is in the closed position and the valve (6) is open, the bowl (2) also being provided with an air supply device (302) which allows limited access of air into the bowl (2), when the lid (362) is in its closed position. 2. System according to claim 1, characterized in that the reservoir (338) forms upper (340) and lower (342) compartments, the water usage unit (40) is connected to the reservoir (338) via a first line (44) opening into the lower compartment (342), the liquid outlet is formed by a second line (328) extending from the lower compartment (342), and that the lower compartment (342) is in throttled connection (via 346) to the upper compartment (340). 3. System according to claim 2, characterized in that the second conduit (328) is formed with a hole (350) opening into the upper compartment (340). 4. System according to one of the preceding claims, characterized in that the air supply device (302) has a flange (304) which extends downwards into the bowl (2), whereby an annular channel (306) is formed between the flange and the bowl (2) and that air supply openings (352) open into this annular channel and the rinsing liquid outlet (324) also opens into this annular channel (306). 5. Toilet module for a transport vehicle, which has a water supply system (42), a suction line (8) and devices for generating a partial vacuum in the suction line (8), which module has a toilet bowl (2) with an outlet opening (4), a normally closed discharge valve (6) with an inflow side connected to the outlet opening (4) of the toilet bowl (2) and an outflow side for connection to the suction line (8), with a flushing liquid outlet (324) for introducing flushing liquid into the toilet bowl (2), a wash basin (40) for receiving water from a water supply system and with a water outlet (44), a reservoir (338) with an inlet (44) for receiving flushing liquid from the wash basin (40) and an outlet (328) in connection with the flushing liquid outlet (324), the toilet bowl (2) having a rim and a toilet bowl lid (362) mounted for movement relative to the toilet bowl (2) between an open and a closed position, which lid (362) is in at least partially sealed relationship with the rim when in the closed position so that when the lid (362) is in the closed position and the dispensing valve (6) is open, a negative pressure is created in the bowl (2), characterized in that the inlet (44) of the reservoir is subjected to substantially the same pressure (P₁) as the flush water outlet (324) when the lid (362) is in the open position and the dispensing valve (6) is closed so that flush liquid is withdrawn from the reservoir (338) via the flush water outlet (324) into the toilet bowl (2) when the lid (362) is in the closed position and the dispensing valve (6) is open, the bowl (2) also being provided with a Air supply device (302) which allows limited access of air into the toilet bowl (2) when the lid (362) is in its closed position. 6. Module according to claim 5, characterized in that the reservoir (338) forms upper (340) and lower (342) compartments, the wash basin (40) is connected to the reservoir (338) via a first line (44) which opens into the lower compartment (342), the liquid outlet is formed by a second line (328) which extends from the lower compartment (342), and that the lower compartment (342) is in throttled connection (via 346) to the upper compartment (340). 7. Module according to claim 6, characterized in that the second conduit (328) is formed with a hole (350) opening into the upper compartment (340). 8. Module according to one of claims 5 to 7, characterized in that the air supply device (302) has a flange (304) which extends downwards into the toilet bowl (2), whereby an annular channel (306) is formed between the flange and the toilet bowl (2), and that air supply openings (352) open into this annular channel and the flushing liquid outlet (324) also opens into this annular channel (306). 9. A method of flushing the toilet bowl of a vacuum disposal system on a transport vehicle, when the system comprises a water usage unit (40), a reservoir (338) being provided to collect water from the water usage unit (40) and means for supplying some water collected in the reservoir (338) as flushing water to the toilet bowl (2), characterized in that the inflow of flushing water to the toilet bowl is accompanied by air flows entering the bowl (2), both the air and water inflows being caused by a negative pressure created in the bowl (2). 10. Method according to claim 9, characterized in that the air currents cause a swirling movement of the rinsing water in the bowl (2).